Scroll to see break-even price per barrel for oil in 2015 for select oil producers, and click on a country's name for more details. modest oil-price recovery and currency devaluations have lowered breakeven prices for countries like Russia and Nigeria, but some petrostates still need oil prices above $100 a barrel to balance their budgets.
There are dozens of types of gemstones â including diamonds, colored gemstones, and pearls â each with a unique set of physical and optical properties. GIRDLE â The narrow band around the perimeter of a polished or faceted diamond or colored gemstone.
However, idiochromatic gemstones are rare. Most gemstones are allochromatic, meaning that they are colored by impurities or trace elements in their crystal structure. For example, pure corundum is colorless. But corundum is typically red when traces of chromium are present and blue when there are traces of titanium.